Here ya go:
1. 3.73 and 275/40R19 were the stock ratio/tire size
2. When Roush added the Stage 3 package to my car, the tires were changed to 275/35R20...about 1/4" smaller circumference than the stock wheels
3. See #2 above...with this small of a change I had no driveability issues/power...
So my speedo would be accurate, I changed the settings, thru FORScan, when I changed tire size. I had the same bog-down/no power in 4th gear as OP and Wolverine are talking about...I did the PCM relearn and codes were cleared and I had full power again.
It appears there may be other issues.
You can buy the plans online from a couple of Ford dealers at a much better price than you can usually get from your local dealer.
Here’s one dealer:
Search on this Forum about using FORScan and you’ll find a couple of threads about making changes to your vehicle...then look at the thread below.
Here is a thread about what changes we’ve been able to make so far:
I looked up the 2016 Roush production numbers and the color/package breakout is the same as the 2017 numbers you posted. Is Roush no longer giving a more detailed breakout of production combinations?